dlnoss

We took some heads to a new anodizing shop to get done in black. Just one color to start with in case we don't like the results. The new shop doesn't do 'bright dipping' which involves dipping the parts in boiling phosphoric acid. Sounds pretty hazardous but made the parts look good. The guy said it shouldn't make much difference since the parts have a good finish to begin with. I think Jeff is wanting some of them. If anyone else does, let me know. I'll post how they look when I get them back. -David

I'd probably add a little octane. 165 psi and +4 timing is pushing it with 91 octane. The extra squish clearance might help but I'd still add at least 20% race gas to be sure. Just my opinion....Could make it less expensive in the long run. -David

I'd be a little worried about 20cc domes at 400' on pump gas.

As long as you run good fresh 93 octane, you should be okay with 21cc domes.

You should be okay with 21cc domes if you run premium pump gas unless your timing is advanced quite a bit. -David

Then your compression should be higher than what was indicated on the tester.

But if the end of the compression tester doesn't thread in as far as the spark plug, the extra thread space inside the dome will add volume to the dome. Maybe I didn't understand everything correctly. Does the adapter have a volume of 1.5cc's between the bottom of the adapter and the check valve of the compression tester when it is threaded on to the end of the compression tester?

Just an estimate but your compression is probably closer to 145-150

The adapter should really lower the reading unless there is a significant airspace inside the adapter itself. If it is only a small hole through the adapter between the cylinder end and the check valve of the tester it shouldn't change the reading much. A leaky check valve in the tester can also give a false low reading.

Yes, 20 ft/lbs in three steps is good on torque. I would be a little suspicious of that compression reading,,,sounds pretty low. Does the compression tester thread in as far as the spark plug? -David

I would say 21cc with premium pump gas but a compression test after it's put back together would be suggested. -David

Less than $3.00/gallon at small Oklahoma airports...$5.50/gallon at larger Dallas airports. Either way, it has lots of lead and lasts a long time before souring.

if you mixed even a gallon of race or av gas with 4 gallons of premium pump gas, you should be fine. There's gotta be a small airport around there somewhere.

I would run at least a mix with 20cc domes and +3/+4 timing at 750'. I also probably would stay with 19cc or larger with a stock crank. Admittedly, I recommend on the conservative side but it gets expensive if you grenade the engine because of detonation or the crank twisting. It can really mess up a good riding trip... Just my opinion for what it's worth. -David

21cc is as small as I'd recommend in Florida with premium pump. Premium pump for sure once you advance the timing.

Something just doesn't make sense. That's more squish clearance AND compression than it should be, which really doesn't make sense. I would have estimated .040" squish and about 160 - 165 psi. Did the domes have '20' engraved on them? Is there a compression tester you could borrow to double check with? Had the engine been run to burn off the assembly lube? Just some ideas...

Also, if the compression tester doesn't thread into the spark plug hole as far as the spark plug, it will give a false low reading.

With the Dyna, I'd go with 20cc domes to be on the safe side.

No Banshee stuff but my wife got me a Rock River Arms LAR-15 with a stainless bull barrel. 3/4" groups at 100 yards. I like it!!!

What octane gas were you running? Race gas I hope. Pull the plugs and check the compression and the appearance of the plugs.

There are lots of variables, among them elevation, porting, compression guages, piston type, etc. One of the things that gets overlooked is the depth that the compression tester threads in to the head/dome. A bunch of the testers have short parts that thread in. If it's shorter than the spark plug threads a false low reading will result. Sometimes just a little more octane is all you need to be on the safe side, like in Washburn's case. I bought 100 octane avgas at a local airport a couple weeks ago for $2.85 per gallon. It has a lot of lead in it and has a very long shelf life compared to pump gas.

If your timing is stock and you run premium pump gas, 21cc should be fine.

I'm here. My spam filter is catching a lot of stuff I want. I checked it and found your emails. I'll check on shipping and email the cost to you. Sorry. -David

When you are comparing prices, remember that BHQ members get a 10% discount making a silver head with domes $234.00 + shipping. -David

I usually ask what elevation, what other mods, what kind of gas. They all play a part in dome selection.